In the second Research Core of this Center, the unifying theme is the use of marine and freshwater model systems for environmental health-related research. In general, the use of model systems as surrogates for the study of pathological states related to the environment stems from several advantages over the direct use of mammalian system. These systems include: 1) Damselfish Neurofibromatosis, 2) Toadfish, 3) Shark Immunology, 4) Aplysia, 5) Transgenic Fishes. The research in the marine models of human diseases is highly interdisciplinary, in that, investigators in this Research Core share knowledge and approaches in several areas on virtually a daily basis. First, there is a great deal of interactivity in basic animal care, maintenance and husbandry techniques. Second, from an experimental standpoint, expertise is available on a number of different levels of biological organization, including biochemistry and molecular biology, pathogen biology, in vitro cell culture and manipulations (including electrophysiology and embryology), and whole-animal physiological and serological methodology. When combined with the interests and expertise available in the Marine and Freshwater Toxins and Human Health Research Core, the investigators believe they are a powerful resource for each of the individual scientists in the MFBS, and for the investigators and mission of NIEHS.